RS5C372A-E2-F Просмотр технического описания (PDF) - RICOH Co.,Ltd.

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RS5C372A-E2-F

I2C bus SERIAL INTERFACE REAL-TIME CLOCK ICs

RICOH Co.,Ltd. 

RS5C372A/B

5.3 Example of Power Supply Wake-up Circuit (RS5C372A only)

The sample circuit below has been designed so that system power supply turns on at a time set in the Alarm_B

using the Alarm_B of the RS5C372A and the RN5RZ××A (RN5RT××A)*1.

System power supply

Backup power supply

RS5C372A

VDD INTRB

OSCIN

OSCOUT

VSS

SCL

SDA

RN5RZ××A or

RN5RT××A *1

VDD VOUT

CE

*3

*2 *3

32.768kHz or 32.000kHz

*4

Microcontroller

VDD

*1) The RN5RZ××A and the RN5RT××A are RICOH regulators with stand-by functions.

*2) The INTRB of the RS5C372A outputs 32-kHz clock pulses on power on. A capacitor is included so that CE will not change to “H” while 32-kHz clock

is off (“H”) to allow the regulator to be turned on.

*3) This resistor is used to prevent excess current from flowing into the pins of the RS5C372A/B and the RN5RZ××A (RN5RT××A) on power on.

*4) Pull-up resistors of the SCL and SDA are not shown in the figure for clarity.

Software Setting

(1) Use periodic interrupt immediately after power on to output ON (“L”) from the INTRB pin.

(2) When you want to turn power off use Alarm_B or periodic interrupt to set a timing for power on and output it

from the INTRB. The INTRB remains off (“H”) until the timing specified, high voltage is applied to the regulator

CE pin thus power for the micro controller is turned off.

(3) On reaching the specified timing, the INTRB pin switches to on (“L”) and power turns on. Hereafter, power is

turned off by setting 0 to the BALFG or the CTFG and turned on again at a next timing specified.

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